A little backstory here

You work in the port mafia, you are a bomb specialist and also a spy. And you have been a good friend with Dazai, so sometimes you go out with him for drinks at the bar to talk from your hearts, and that's how you met Ango and Oda (Odasaku). Today you came into the bar you usually meet Dazai but he's not here today also... Ango is not here, only Oda

Oda notices you and waves to you in a greeting manner